This invention relates to an electrical connector for use in inspecting integrated circuits used in high-speed transmission as in mobile phones, and more particularly to an electrical connector capable of minimizing irregularities in measured values of electrical characteristics of integrated circuit pads even if contact points of contacts of the connector on the pads are unexpectedly shifted.
In inspecting integrated circuits, a hemispherical or other shaped electrical contact provided on a connector has been brought into contact with an integrated circuit pad at a single point to perform its inspection in the past as explained in the following patent literatures. For example, in Japanese Patent Application No. 2002-228,911 (Patent Literature 1), belonging to the applicant of the present application has proposed an electrical connector which is well-adapted to high-speed transmission signals and enables a reliable connection between fine conductive wires 20 and a flexible printed circuit board 18 without any need to give an attention to lengths of the fine conductive wires and without any risk of the flexible board being deflected or warped. In the proposed electrical connector, connection portions of conductors can be readily connected to the flexible printed circuit board 18 even if circumferences of the connection portions to be electrically connected are covered by insulators. The electrical connector achieves such effects by comprising an elastomer layer 22, a plurality of fine conductive wires 20 embedded in the elastomer layer 22 and extending rectilinearly therein at right angles to both surfaces of the elastomer layer, and recesses 26 being formed in the elastomer layer 22 around peripheries of openings of holes in which the fine conductive wires are embedded. This patent application further discloses a feature of clamping the flexible printed circuit board 18 and the elastomer layer 22 by means of restraining jigs 32 when the flexible circuit board 18 and the fine conductor wires 20 of the elastomer are electrically connected by vapor reflow soldering, thereby preventing the connection portions of the flexible printed circuit board at both the surfaces from moving away from the elastomer 22.
The applicant of the present application has also proposed an electrical connector for inspecting chips to reduce its cost remarkably in Japanese Patent Application No. 2003-133,231 (Patent Literature 2). For chips obtained by individual dicing of wafers, it is required to identify front and rear faces, top and bottom, and right and left of the chip preparatory to measurement of characteristics so that expensive means for such an identification are required as well. Based on the recognition that the cost can be remarkably reduced by performing the inspection under the state of wafers, the applicant has proposed the following features in that application. A plurality of fine conductive wires 20 are embedded in an elastomer layer 22 to extend rectilinearly therein at right angles to both surfaces of the elastomer layer. The elastomer layer 22 is formed with recesses 26 around peripheries of openings of holes in which the fine conductive wires 20 are embedded, respectively. The overall lengths of the fine conductive wires 20 are substantially equal to or slightly larger than the thickness of the elastomer 22 so that both the ends of the wires 20 slightly extend from the both surfaces of the elastomer 22. A flexible printed circuit board 18 having electric contacts 12 is connected to the fine conductive wires 20 of either of the surfaces of the elastomer 22, or a hard board or substrate 30 is connected to the surface of the elastomer opposite to the surface connected to the flexible printed circuit board 18.
Moreover, Japanese Patent Application Opened No. H10-69,955 (1998) (Patent Literature 3) discloses an integrated circuit socket for inspecting integrated circuits having projection electrodes such as bump electrodes, a testing method using the integrated circuit socket, and an integrated circuit socket mounting mechanism. The integrated circuit socket is mounted on a test substrate 32 for performing the tasting of the integrated circuit with a high accuracy without damage to the miniaturized projection electrodes, and is adapted to be provided with the integrated circuit 25 having solder bumps 28 to be tested. The integrated circuit socket comprises a contact unit 23 consisting of a plurality of straight contact pins 30 whose lower ends are electrically connected to the test substrate 32 and upper ends are connected to the solder bumps 28, and an elastic member 31 supporting these contact pins 30. Further, the contact pins 30 have a fine diameter capable of piercing the solder bumps 28 so that their electrical connection can be achieved by the piercing thereinto.
Furthermore, Japanese Patent Application Opened No. H11-297,444(1999) (Patent Literature 4) discloses a test socket which attempts to eliminate problems associated with test socket arrangement of the prior art. The test socket for integrated circuit packages of the opened application comprises an upper housing and a lower housing clamped to the top and bottom surfaces of a mounting substrate, respectively. The upper housing includes a cavity for receiving an integrated circuit package and holes at the bottom of the upper housing for bringing a plurality of solid socket plungers into contact with testing positions of the integrated circuit package. The socket plungers are arranged in a plurality of grooves formed in the lower housing and extend through a plurality of holes of the mounting substrate to contact the test positions. A plurality of springs are arranged in the plurality of grooves of the lower housing under the plungers to resiliently urge the plungers upwardly with the aid of balls arranged between the springs and inclined end faces of the plungers.
Japanese Patent Application Opened No. 2000-8,749 (Patent Literature 5) discloses an electrical connector which intends to prevent irregularities in resistances at connection portions, to stabilize the connection of electrodes and to prevent excess deformation by compression. This opened application further discloses a connection structure using this electrical connector, and a semiconductor socket and a method for producing the same. The connection structure comprises a fitting plate 8 interposed between a mounting circuit board 4 and a semiconductor package 30, an electrical connector 12 to be fitted in the fitting plate 8, and a positioning plate 17 overlapping the fitting plate 8. The electrical connector 12 comprises an elastic insulating sheet 13 to be fitted in the fitting plate 8, a plurality of elastic connection elements 14 arranged at a predetermined interval and extending from the elastic sheet 13 toward the semiconductor package 30, and a plurality of metal ribbons 15 built-in the respective elastic connection elements 14 so as to correspond to the mounting circuit board 4 and a plurality of electrodes 5·31 of the semiconductor package 30 in a manner achieving the continuity between the mounting circuit board 4 and the electrodes 5·31 of the semiconductor package 30. The respective metal ribbons 15 are straight inclined in the same direction as the opposed direction of the mounting circuit board 4 and the semiconductor package 30, and the positioning plate 17 is formed with position correcting slits 18 through which the respective elastic connection elements 14 extend.
Japanese Patent Application Opened No. H6-243,940 (1994) (Patent Literature 6) discloses a CDDI connector whose electrical characteristics are improved to comply the requirements imposed on high-speed network parts. This opened specification discloses the feature of arranging contacts 13 of the connector (CDDI connector) for a high-speed network for transmitting audio and data signals on an inner circle 3 and an intermediate circle 2.
In the method for inspecting an integrated circuit pad having a certain size by bringing only a single contact of a connector for the inspection into contact with the pad as in the patent literatures 1 to 5 described above, the conductive path length will be changed depending upon contacting positions of the single contact on the pad. Consequently, there would be a tendency of irregularities in measured values such as disclosed electric resistance values and skews to occur in the inspection, resulting in unstable inspection.